Optical recording medium having a relationship between groove width and track pitch

Abstract

An optical recording / reproducing medium having grooves formed along recording tracks and used for recording / reproducing when irradiated with light L with a specified wavelength λ, wherein the track pitch p of a groove is at least 200 nm and up to 350 nm, and a ratio wg′ / p between the width wg of a groove and a track pitch p is at least 0.24 and up to 0.67.

Description

TECHNICAL FIELD[0001]The present invention relates to an optical recording and reproducing medium substrate suitable, a manufacturing method of optical recording and reproducing medium manufacturing stamper and an optical recording and reproducing medium manufacturing stamper for use with an optical recording and reproducing medium having grooves formed along recording tracks.BACKGROUND ART[0002]Various kinds of optical disks shaped like discs for optically recording and / or reproducing information are put into practical use as optical recording and reproducing mediums. A read-only optical disk having embossed pits formed on a disk substrate beforehand, a magneto-optical disk for recording data by magneto-optical effect and a phase-change optical disk for recording data by phase-change of a recording film are available as such optical disks.[0003]Of these optical disks, in the optical disk in which data can be written, such as a magneto-optical disk and a phase-change optical disk, i...

AI Technical Summary

Benefits of technology

The present invention provides an optical recording and reproducing medium substrate with grooves that have optimized track pitch and ratio between groove width and track pitch, resulting in stable push-pull signal amplitude and high recording density. The substrate also has microminiaturized groove patterns and surface roughness, as well as an inclination angle of the groove side surface and depth of the groove within specific ranges. The manufacturing method of the substrate includes exposing a master substrate with a pattern corresponding to the groove tracks, developing a master, and etching a stamper for molding the substrate. The substrate can hold satisfactory recording and reproducing characteristics.

Problems solved by technology

However, the high density optical disks of the DVD+RW, DVD-R, DVD-RW and the like have the groove widths smaller than the recording wavelength (413 nm), i.e., the ratios between the groove width and the recording wavelength smaller than 1.0 so that these groove widths cannot be formed relatively easily.

However, there has not yet been proposed an ultra-high density optical disk manufacturing method which is not only excellent in productivity in actual practice but also satisfactory in yield.

Therefore, this conventional manufacturing method cannot be directly applied to an optical disk that intends to increase recording density by reducing the track pitch to less than about 350 nm.

There is then a risk that a leakage of a signal will occur when a wobble signal is reproduced.

Thus, a problem arises, in which it will be difficult to form wobbling grooves at a level suitable for actual practice.

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